This invention relates to a system for improving the quality of steel in the casting process. More particularly, this invention relates to improvements in the transfer of molten metal from a ladle to a tundish. More specifically, the present invention assures a sealed connection between the ladle and the tundish to prevent air from contacting the molten metal, and in another aspect, prevents the molten metal from being contaminated with slag from the tundish.
In the steel-casting process, molten metal is transferred from the furnace to a ladle which is then transported to the area of a tundish. Several ladles typically provide the molten metal to one tundish which, in turn, provides the molten metal to a continuous casting machine. The top surface of the metal, in both a ladle and in the tundish, is normally provided with a layer of slag to, among other things, prevent the contact of air with the molten metal inasmuch as it is very deleterious to the quality of the end product, the cast steel, if the molten metal has absorbed any oxygen or nitrogen.
Typically, a ladle full of molten steel is conveyed to a location over the tundish. The ladle carries a normally closed downwardly directed refractory nozzle through which the molten metal will ultimately be expelled through a refractory tube and into the tundish. The tube is positioned, by a steelworker, adjacent to the nozzle, and once the tube is properly aligned with the nozzle, it is fixed in position. The ladle and tube are then lowered into the tundish, with the tube extending through the slag layer on top of the molten metal already in the tundish. The ladle nozzle is then opened and the molten metal flows through the nozzle and the tube and into the tundish. Molten metal from the bottom of the tundish is continually being transferred to a steel casting machine. When the ladle has transferred its load of molten metal to the tundish, it is raised to its original position, the tube is removed, and it is conveyed away as the tundish awaits its next load of molten metal from the next ladle at which time the whole process is repeated.
A problem relating to the contamination of the molten metal with air exists with the aforedescribed process. The bottoms of known ladle nozzles are provided with a conical surface which is intended to be aligned with, and thereby perfectly match, a conical surface formed at the top of the tube so that air cannot pass between the nozzle and the tube. The problem is, however, that such perfect alignment between the nozzle and the tube is not readily obtained. Since the steelworker cannot get too close to the ladle and the tundish, the tube is usually connected, in a gimbal-like fashion, to the end of a long rod. The tube must then be maneuvered into attempted alignment with the nozzle of the tundish before being locked in place. But if, as is often the case, the alignment is not perfect, the conical surface of the nozzle and the tube will not perfectly mate. As a result, a gap is formed whereby air can come into contact with the molten metal as it passes from the ladle to the tundish.
Another problem exits in known steelmaking systems which relates to the potential contamination of the molten metal by the slag in the tundish. With the tube positioned adjacent to the nozzle, as the ladle is lowered to insert the tube through the slag and into the molten metal in the tundish, it is highly likely that slag will back up and be received within the tube. Then, when the ladle nozzle is opened, the molten metal from the ladle will pass through the nozzle and tube, thereby expelling the slag in the tube into the molten metal in the tundish. Such adversely effects the quality of the resulting cast steel.
In short, the need exists to improve the quality of steel in the casting process by eliminating these problems at the area of the transfer of the molten metal from a ladle to the tundish.
It is thus a primary object of the present invention to provide a system to improve the quality of cast steel.
It is another object of the present invention to provide a system, as above, which does not permit the molten metal to be exposed to air when being transferred from a ladle to the tundish.
It is a further object of the present invention to provide a system, as above, which prevents any air gap between the nozzle of a ladle and the tube which is inserted into the molten metal of the tundish irrespective of the precise alignment between the nozzle and the tube.
It is an additional object of the present invention to provide a system, as above, which does not permit the slag, which covers the molten metal in the tundish, to contaminate that molten metal.
It is yet another object of the present invention to provide a system, as above, which prevents the tundish slag from being received in the tube before the molten metal in a ladle is permitted to pass through the tube.
These and other objects of the present invention, as well as the advantages thereof over existing prior art forms, which will become apparent from the description to follow, are accomplished by the improvements hereinafter described and claimed.
In general, in accordance with one aspect of the present invention, a system for transferring molten metal from a ladle to a tundish includes a nozzle having a first end communicating with the ladle and having a second end. A tube has a first end adapted to be positioned adjacent to the second end of the nozzle and has a second end adapted to communicate with the tundish. Either the second end of the nozzle or the first end of the tube is generally spherically shaped so as to form a seal between the tube and the nozzle such that the molten metal may pass through the nozzle and the tube and into the tundish.
In accordance with another aspect of the present invention, a system for transferring molten metal from a ladle to a tundish includes a nozzle having a first end communicating with the ladle and having a second end. A tube has a first end adapted to be positioned adjacent to the second end of a nozzle and a second end adapted to communicate with the tundish. A plug is adapted to be positioned in the second end of the tube such that when the molten metal passes from the ladle through the nozzle and the tube, the plug is displaced from the second end of the tube and the molten metal is received in the tundish.
The method of transferring molten metal from a ladle to a tundish utilizing the system includes the steps of positioning the ladle over the tundish, positioning one end of a tube adjacent to one end of a nozzle carried by the ladle, sealing the junction between the nozzle and the tube by forming one of the ends with a spherical surface, lowering the ladle, nozzle and tube toward the tundish, and thereafter allowing the molten metal to pass through the nozzle and the tube and into the tundish.
The system has applications for transferring a fluid from a first container to a second container wherein a first tubular member has a first end communicating with the first container and has a second end. A second tubular member has a first end adapted to be positioned adjacent to the second end of the first tubular member and has a second end adapted to communicate with the second container. Either the second end of the first tubular member or the first end of the second tubular member is generally spherical so that when the second end of the first tubular member and the first end of the second tubular member are positioned adjacent to each other, a seal is formed between the first and second tubular members.
A preferred exemplary system for transferring molten metal from a ladle to a tundish according to the concepts of the present invention is shown by way of example in the accompanying drawings without attempting to show all the various forms and modifications in which the invention might be embodied, the invention being measured by the appended claims and not by the details of the specification.